Transcript PH1600: Introductory Astronomy

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PH1600: Introductory Astronomy
Lecture 22: In the Beginning …
PH1600: Introductory Astronomy
Lecture 21: The Beginning of Our Universe
Study: Chapter 19 in The Cosmos book
Next Lecture: Chapter 19: Early Forces & Inflation
School: Michigan Technological University
Professor: Robert Nemiroff
Book: The Cosmos by Pasachoff & Filippenko
Online Course WebCT pages:
http://courses.mtu.edu/
This class can be taken online ONLY, class
attendance is not required!
You are responsible for…
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Reading the book
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APODs posted during the semester
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One chapter per “quiz period”
Anything from that chapter can appear on
quizzes or tests, even if I never mention them
during my lecture(s)
This quiz period covers Chapters 18
APOD review every week during lecture
Completing the Quizzes
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Chapter 1, 2, 4, 6, 7, 8, 10, 11, 13, 14, 15 &
18 quizzes already due
Chapter 19 quiz due next
See WebCT at http://courses.mtu.edu/ for
details
Universe Beginning:
Steady State of Big Bang?
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Steady State Universe
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Perfect cosmological Principle: universe
does not evolve with time
Big Bang Universe
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Universe evolves in time
Cosmological Principle: universe looks
the same from every location
Microwave Background Radiation
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Penzias & Wilson try to map Galaxy
radio emission with horn shaped
antenna
Find strange hiss in all directions
Can’t eliminate it
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Not warm pigeon poop
Can’t explain it
Horn Antenna used by Penzias and Wilson to detect the cosmic
microwave background radiation.
http://www.phys.lsu.edu/~tohline/astr1102/Pics/Fig28-05.jpg
Microwave Background Radiation
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Photons from when the universe
was only 400,000 years old
Originally 3000 K, now only 2.7 K
Show that Earth is moving with
respect to CMBR
Spot distribution shows universe is
70% dark energy, 13.7 billion years
old
CMBR Dipole: Speeding Through the Universe
Credit: DMR, COBE, NASA, Four-Year Sky Map
APOD: 2006 October 8
COBE All-Sky Map
Credit: COBE Project, DMR, NASA
APOD: 2006 October 7
Antarctica Hears Little Normal Matter in the Big Bang
Credit & Copyright: DASI, CARA, NSF
APOD: 2001 May 1
The Race to Reveal Our Universe
Credit: BOOMERANG Project, NSF
APOD: 2000 May 9
WMAP Resolves the Universe
Credit: WMAP Science Team, NASA
APOD: 2005 September 25
The Big Bang
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t<10-43 seconds
Planck epoch
Before Planck epoch, the general
relativity description of spacetime
breaks down.
No one knows what happens before
10-43 seconds
The Big Bang: Energy Everywhere
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10-43 < t < 10-6 seconds
Universe expands and cools
1032 < T < 1013 Kelvin
Radiation epoch
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All particles have speed near light
Nuclei not stable
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Broken apart soon after forming
The Big Bang: Particles Freeze Out
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10-6 < t < 1 second
Universe expands and cools
1013 < T < 1010 Kelvin
Protons, neutrons, electrons,
positrons now frozen in
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All particles have speed near light
Nuclei not stable
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Broken apart soon after forming
The Big Bang: Nuclei Freeze Out
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1 < t < 100 seconds
Universe expands and cools
1010 < T < 1013 Kelvin
Nuclei become stable
Primordial nucleosynthesis
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Determines what nuclei remain in the
universe
Universe mostly hydrogen & helium
The Big Bang: Nuclei Become Atoms
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t = 400,000 years
Universe expands and cools
T = 3000 Kelvin
Recombination
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Atoms become stable
Nuclei able to retain electrons
Photons fly free for first time
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Still flying – form microwave
background radiation today
The Big Bang:
Formation of Stars and Galaxies
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400,000 < t < 4,000,000 years
Dark Ages
Stars not yet formed
4 million years < t < 13.7 billion
years
Stars form, galaxies form
Universe cools to 3.7 Kelvin
http://en.wikipedia.org/wiki/Image:Universe_expansion.png
Inflating the Universe
Credit: WMAP Science Team, NASA
APOD: 2006 March 23
http://en.wikipedia.org/
wiki/Image:
Cosmological_composition.jpg
The Big Bang: Epochs
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Radiation dominated
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Matter dominated
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Photon-like energy most abundant
t < 300,000 years
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Atoms, molecules, dark matter most abundant
300,000 < t < 5 billion years
Dark energy dominated
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Now (barely)
The Hubble Deep Field
Credit: R. Williams, The HDF Team (STScI), NASA
APOD: 2002 September 1
The Andromeda Deep Field
Credit: T. M. Brown (STScI) et al., ESA, NASA
APOD: 2003 May 19
HUDF: Dawn of the Galaxies
Credit: R. Windhorst (ASU), H. Yan (SSC, Caltech), et al., ESA, NASA
APOD: 2004 September 29